1. Field of the Invention
The present invention relates to a tank container comprising a container for a liquid to be stored or transported, a pipe circuit comprising a heat transfer circuit part mounted to the wall of the container, which pipe circuit is filled with glycol, a storage vessel connected to the pipe circuit for holding an amount of glycol, a heating device designed for selectively heating the glycol in the pipe circuit, and a pump in the pipe circuit for circulating the glycol.
2. Description of Related Art
As a rule, the container is a substantially cylindrical tank, for example having a diameter of about 2.5 meters, a length of about 6 meters and a capacity of about 26,000 liters, which tank is often mounted in a block-shaped frame having an ISO 20 feet dimension.
Usually, such heating systems for tank containers use a cooling medium consisting of a mixture of glycol and water mixture in a proportion of about 1:1, the maximum temperature of the mixture being 100° C. If a cooling medium temperature of between 100° C. and 140° C. is required, the cooling medium will have to consist of at least substantially 100% pure glycol, because the boiling point of pure glycol is well above 150° C. The drawback of pure glycol is that it has a high viscosity at lower temperatures (below 25° C.), so that pumping it is difficult and gradually becomes impossible. This is problematic especially if the heating system has been off for some time and circulation of the cooling medium must be started.